US 8235978 B2
A system and tool for performing a capsulotomy procedure. The system includes an air pressure unit, a capsulotomy and movement control unit providing electrical current and movement control, and a capsulotomy tool, and an extendable-retractable burning element coupled to the tool. A capsulotomy and movement control unit provides electrical current to the burning element and movement control for extending and retracting the burning element. When the burning element is in a flattened, retracted configuration, the tip of the tool can be inserted through a relatively small corneal incision. Then, the burning element is opened to a circular, extended configuration, allowing a capsulotomy by applying an electrical pulse to the burning element. Optionally, predefined points of weakness allow removal of the tool should breakage occur during surgery.
1. A tool for performing a capsulotomy, comprising;
(a) a main housing having a proximal end and a distal end;
(b) an inner tube extending longitudinally through said main housing and extending from the distal end of said main housing;
(c) an outer tube that extends longitudinally through said main housing and extends from said distal end of said main housing, wherein said inner tube is disposed inside of said outer tube, and wherein said inner tube is movable with respect to said outer tube
(d) an extendable-retractable burning element, comprising first and second electrically conductive bands, said bands having opposite ends that are connected between the end of said inner tube and the tip of said outer tube, said burning element being adapted for switching between a retracted configuration and an extended configuration, by said movement of said inner tube with respect to said outer tube;
(e) a groove present on each of said first and second bands, said grooves providing predefined points of weakness allowing for controlled breakage of said burning element at said grooves, during an event of excessive electrical current;
(f) an airflow channel extending through said main housing and terminating proximal to said burning element;
(g) airflow means coupled to the airflow channel for supplying pressurized airflow; and
(h) capsulotomy and movement control means coupled to the main housing for providing electrical current to the burning element and movement control for controlling extending and retracting of the burning element,
wherein said retractable burning element is insertable into the eye through a small corneal incision when said burning element is in a retracted configuration, and said burning element is adapted to perform of a capsulotomy of a predetermined size when it is in an extended configuration and an electrical current is applied to said burning element.
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4 mm, 5 mm, 6 mm and 7 mm.
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18. A system for performing a capsulotomy procedure, comprising;
(a) the capsulotomy tool of
(b) a capsulotomy and movement control unit;
wherein said tool is in connection with said capsulotomy and movement control unit for providing electrical current and movement control to said burning element such that when said burning element is extended and heated, an opening is burned on the lens capsule.
19. The system of
20. The system of
The present application is a Continuation-in-Part of U.S. patent application Ser. No. 11/911,111 filed Mar. 11, 2009 by the Applicant.
The present invention relates to a field of cataract surgery. More specifically, the present invention relates to a system and tool for performing a capsulotomy procedure.
To date, over one million cataract surgeries are performed annually in the United States, in which the anterior lens capsule must be opened to gain access to the lens nucleus and allow removal of degenerated cortical material. It is necessary to create a relatively large circular opening in the lens capsule in order to enter the lens interior and to withdraw matter from inside. Formation of this opening is known as a capsulotomy. It is important that the opening has smooth edges and is tear resistant so that the lens contents can be easily removed through the opening. The lens opening is usually on the order of 5-7 millimeters in diameter, though this may vary.
Currently, two techniques for anterior capsulotomy are widely used: the “can-opener” technique and capsulorrhexis. In can-opener capsulotomy, a small incision in the sclera or peripheral cornea is performed, then a cystotome, knife, or needle is inserted through the incision and small connecting tears are made in the anterior lens capsule in a circular pattern. After a complete circle has been made by connecting the tears, a circular piece of the anterior capsule is grasped with forceps and torn away along the perforations. Unfortunately, when opening the capsule with numerous small capsular tears, the small tags that remain become a focal area of least resistance and can lead to tears, which extend radially and posteriorly to the posterior capsule. The detrimental result is a loss of structural stability of the capsule and an increased likelihood of vitreous entry into the anterior chamber.
Capsulorrhexis denotes a circular central opening in the anterior capsule. This continuous opening eliminates the residual tags common with the can-opener technique described above. In capsulorrhexis, a capsular incision is made with a cystotome, and this incision is coaxed to form a circular shape by pushing the leading edge of the freshly tearing capsule with the cystotome in a non-cutting fashion or by grasping the leading edge with forceps. This procedure is challenging for the surgeon to control. The tearing motion can lead to an undesirable tear toward the equator and the posterior capsule, and the size of the opening is difficult to dictate. Capsulorrhexis requires a significant amount of skill and experience and to consistently obtain successful results.
Opening the anterior capsule via either of the described techniques of anterior capsulotomy is a delicate procedure and is widely considered to be one of the most difficult steps in cataract surgery. A poorly performed anterior capsulotomy significantly hinders the subsequent surgical steps and increases the probability of operative complications. Complications resulting from a poor capsulotomy include zonular stress with subsequent breakage of the posterior capsule, vitreous loss, and large capsular tags preventing efficient lens removal. A poor capsulotomy also prevents placement of an intraocular lens in the capsular bag due to ill-defined capsular structures. The operative time is lengthened and patient discomfort can be increased, along with the risk of postoperative complications and decreased visual acuity results.
With either of the above-described techniques for anterior capsulotomy, the size or position of the capsular opening is often not ideal. The location, size, and configuration of the incision have important consequences. For example, an overly small capsular opening can impair the safe removal of the lens nucleus and cortex and prevent proper intraocular lens insertion into the lens capsule. In addition, a small or eccentric capsular opening places excessive stress on the lens capsule during surgery, placing the eye at risk for zonular and capsular breakage.
Certain devices have been proposed to overcome the problems associated with conventional anterior capsulotomy techniques. For example, U.S. Pat. No. 4,766,897 issued to Smirmaul, and U.S. Pat. Nos. 5,269,787 and 5,873,883 issued to Cozean Jr. et al. each disclose instruments that include circular cutting members for incising the anterior capsule. However, use of such devices in small incision cataract surgery is limited due to their size. Specifically, the anterior lens capsule of the eye is shielded by the cornea and sclera, such that a passage wound must be cut in the corneal or scleral tissue before any surgical apparatus can reach the anterior capsule. It is desirable to limit the width of the passage wound incised on the corneal tissue, preferably to 1-3 millimeters. A small wound decreases the scope of the surgical closing procedures, promotes rapid healing, minimizes astigmatism, reduces potential infections, and offers rapid visual rehabilitation. Therefore, the instrumentation employed in cataract surgery should be capable of passing through a small wound. Prior art cutting members cannot be passed through a small corneal incision of 1-3 mm.
Burning tools exist in which heat is concentrated at the tip, and the tip is made to contact and burn a surgical site. In use of such burning tools for cataract surgery, an incision is made in the cornea, and the tip of tool is inserted through the incision and brought into contact with the capsule, where it is activated to sear through the capsule. The use of prior art burning tools is restricted by the small size of the incision, as previously mentioned, which hampers introduction of a large tip having a circular shape of the appropriate size of the desired seared area.
International application PCT/IL05/000461 by the Applicants describes a burning ring present at an oblique angle on the end of a narrow-diameter shaft. The burning ring can therefore be introduced through a small incision, and the oblique angle grants a relatively large elliptical burn, with the largest axis of the burn being larger than the diameter of the shaft.
U.S. Pat. No. 6,066,138 to Sheffer et al. describes a searing cautery that is retractable from within a handle, so that the cautery can be extended to its final size after insertion through the corneal incision. The Sheffer patent suffers from the disadvantage that the burning ring does not close a complete circle, as apparent in
Other burning tools exist which have a small diameter tip, which is inserted through the incision, and used to burn a series of holes in the capsule, arranged in a ring, which is then grasped with forceps and torn into a circular opening. It is difficult to manipulate the burning tool to form a series of burns that are reliably ring-shaped and are present at the desired location, and form a ring of the desired size. Also, in cataract surgery, the procedure is usually complicated by the need for multiple instruments: a cutting tool, an air pressure inlet, a water pressure inlet, and related surgical and electrical equipment.
My previous invention, described in International Publication No. WO 06/109290, disclosed a surgical tool which provides both regulated heating and airflow pressure directed to a surgical site. The tool is capable of passing through a relatively small corneal incision and can easily form a large diameter ring-shaped opening in the capsule.
The tool overcame the need for multiple instruments in cataract surgeries as it provides both regulated heating and airflow pressure directed to a surgical site. Furthermore, the tool is convenient to handle, can be inserted through a small diameter (1-2.8 millimeters) incision in the cornea, and is capable of reliably creating a uniform circular-shaped opening of approximately 4-7 millimeters in the lens capsule.
The surgical tool described in WO 06/109290, overcomes major problems associated with prior art tools. However, the scenario in which the tool breaks while in the eye, was not addressed in my previous patent, and since the possibility of failure during surgery always exists, the design of the tool should be such that in case of breakage, it will be possible to remove the tool immediately from the eye without damage to the eye.
The present invention enlarges on the previous concept, describing a design aspect allowing straightforward removal of the tool from the eye in case of breakage of the tool during surgery, without damage to the eye.
Accordingly, it is a principal object of the present invention to provide a thermal system and tool for the performance of a capsulotomy that effects formation of an opening in the lens capsule through the use of a short pulse of electrical current. The heat generated from the current instantaneously burns an opening of a predetermined size in the lens capsule.
Moreover, the system and tool of the present invention is adapted for maintaining a pressurized airflow to the surgical site so that additional airflow control devices are not required.
Additionally, the system and tool of the present invention has an expandable-retractable burning element that enables approaching the lens through a small corneal incision (about 1.5 millimeters) while allowing for a capsulotomy having a diameter, for example, of about 5-7 millimeters.
In accordance with a preferred embodiment of the present invention, there is provided a system for performing a capsulotomy procedure, comprising a capsulotomy tool comprising a main housing having a distal end and an extendable-retractable burning element coupled to the distal end of the main housing and a capsulotomy and movement control unit. The capsulotomy tool is in connection with the capsulotomy and movement control unit for providing electrical current and movement control to the burning element such that when the burning element is extended and heated, an opening is burned on the lens capsule.
According to a preferred embodiment of the present invention, the burning element comprises first and second electrically-conductive bands having opposite ends that are connected between the end of the inner tube and the tip of the outer tube.
In a preferred embodiment, the first and second bands each have a groove upon them, with the groove representing a predefined point of weakness. In the undesirable scenario in which the electrical current is excessively high, breakage will occur at these predefined points of weakness. Should this occur while the tool is within the eye, the location of the grooves upon the bands is such as to nevertheless allow retraction of the broken bands into the sleeve prior to the removal of the tool from the eye. The tool can be immediately removed from the eye without damaging the eye. Preferably, a single groove is present on each band, and each groove is situated near the end of its respective band, close to the tip of the outer tube. The broken bands thus remain connected at the end of the inner tube, and can be retracted and removed from the eye.
According to preferred embodiments of the present invention, the system also comprises a handle for connecting between the tool and the capsulotomy and control unit. The burning element for performance of the capsulotomy is retracted from the capsulotomy tool portion beyond the handle, and this tool portion is for disposable, one-time use.
According to further preferred embodiments of the present invention, the system also includes an air pressure unit and airflow means coupled to the air pressure unit for directing pressurized air to the surgical site.
In accordance with another preferred embodiment of the present invention, there is provided a tool for performing a capsulotomy, comprising;
Other features and advantages of the present invention will become more readily apparent and understood from the detailed description section that follows.
For a better understanding of the invention with regard to the embodiments thereof, reference is made to the accompanying drawings, in which like numerals designate corresponding elements or sections throughout and in which:
The present invention discloses a capsulotomy tool, which has a retractable cautery ring, also known as a burning element. The burning element is initially hidden within a sleeve. After the tool is inserted past the capsular incision, the burning element is progressively extended from within the sleeve by sliding outwards several concentrically arranged tubes with which the element is associated. Finally, the burning element is fully opened to expand into a complete circular or complete oval shaped cautery, which is then heated to sear the lens. The complete circular or oval-shaped searing thus eliminates the need for tearing by forceps, which is potentially dangerous and difficult to perform.
In the invention, heating is limited to the burning element, so there is no danger of searing inappropriate areas of the eye. The retractable nature of the burning element allows it to be introduced through a small capsular incision, yet provides burning on the lens at a diameter larger than that of the small capsular incision. The tool additionally provides pressurized airflow through its hollow center, alleviating the need for a separate airflow tool.
Capsulotomy tool 10 includes a sleeve 52 that extends from distal end 14 of main housing 12. Initially, sleeve 52 is disposed over surgical elements of capsulotomy tool 10, to be described further herein. Sleeve 52 is formed from a non-conductive material, such as plastic or Teflon, and has smooth sides such that entry into the eye can be achieved with minimal friction. The end of sleeve 52 is tapered around the edges. This serves to ease of entry into the eye after an incision has been made. Sleeve 52 also provides a seal against the corneal incision after the eye has been entered.
Capsulotomy tool 10 also includes an inner tube 20 that passes through the central axis of main housing 12, and that extends from distal end 14 of main housing 12 and through outer tube 18. The hollow center of inner tube 20 defines an air channel 24 (see
According to a preferred embodiment, all elements shown in
Burning element 30 includes a first band 34 and a second band 36, which are formed from electrically conductive material such as, though not limited to, a tungsten alloy. The opposite ends of each band 34, 36 are vertically connected between the end of inner tube 20 and tip 46 of outer tube 18. Movement of inner tube 20 in the direction of tip 46 of outer tube 18 causes first band 34 and second band 36 to adopt the extended and open configuration, in which bands 34, 36 substantially form a circle with one another, as shown in
Sleeve 52 covers outer tube 18 and inner tube 20 during passage of the tip of the capsulotomy tool 10 through the corneal incision. By providing sleeve 52 as a cover for outer tube 18, as well as for inner tube 20 and burning element 30, the entry into the eye can be accomplished quickly and with minimal friction.
As mentioned previously, sleeve 52 also serves the purpose of providing a seal against the cornea once the end of capsulotomy tool 10 has been inserted into the eye. It will be noted that in
In the retracted configuration, bands 34, 36 of burning element 30 are positioned substantially flattened and parallel to one another, directly above extension 48 of outer tube 18. In
The height of bands 34, 36 is about 200 microns higher than that of inner tube 20 and tip 46, so that when the edges of bands 34, 36 contact the capsule, no other elements of capsulotomy tool 10 will contact it. Inner tube 20 is provided with a slot 60 formed in the upper edge at the end thereof for accommodating the additional height of bands 34, 36.
Optionally, before use the burning element 30 is removed from the tool 10, so that the size of the burning element can be selected in order to choose the size of the capsulotomy. Preferably, several removable burning elements can be designed having longer or shorter bands, in order perform a capsulotomy having a diameter selected from most preferred diameters 4, 5, 6 or 7 mm. Removable burning elements of other sizes can also be envisioned.
First and second bands 34, 36 are formed from electrically conductive material such as a tungsten alloy or any other suitable element. Inner tube 20 and outer tube 18, are both formed, at least partially, from electrically-conductive material. Extension 48 and tip 46 of outer tube 18, are likewise formed from the same material. Inner tube 20 and outer tube 18 define opposite poles of an electrical circuit, and they are designed so as to be electrically insulated from one another.
To perform a capsulotomy, a brief low-voltage electrical pulse is passed through bands 34, 36. When a current is passed through inner tube 20, bands 34, 36, tip 46, extension 48, and returning through outer tube 18, bands 34, 36 will heat up (or vice versa depending on the polarity).
It will be appreciated that a switch is provided such that the electrical circuit can be completed only when burning element 30 is in the extended configuration, so as to prevent premature heating of burning element 30.
Reference is now made to
Capsulotomy tool 10 is coupled to a handle 72 which facilitates maneuvering of tool 10 by the surgeon. Handle 72 houses a motor (not shown) that is connected to spring mechanism (54, see
Handle 72 is coupled to an air pressure unit 74 via an air tube 76 having a connector 96 at the end thereof, for supplying pressurized air to the surgical site during performance of the capsulotomy. Air pressure unit 74 preferably includes a control 78 and a display 80 for determining the amount of pressurized air delivered to the air channel of capsulotomy tool 10.
Handle 72 is further coupled to a capsulotomy and movement control unit 82 via a power cable 84 having a connector 94 at the end thereof, for supplying electrical current and movement control to capsulotomy tool 10. Capsulotomy and movement control unit 82 also includes a control 86 as well as a display 88 for determining the amount of electrical current applied through power cable 84 to capsulotomy tool 10. Power cable 84 is connected to the motor inside of the handle 72 for facilitating movement of the outer tube 18 and inner tube 20 of capsulotomy tool 10.
A foot-pedal control switch 90 is also connected to capsulotomy and movement control unit 82 via a cord 92. Foot-pedal control switch 90 enables the surgeon to control the movement of the inner and outer tube 20, 18 and the extending and the retracting of the burning element 30, as well as applying of electrical current, with his foot.
Operation of capsulotomy tool 10 will now be described, when used for creation of a seared capsulotomy opening during cataract surgery.
With burning element 30 thus extended and circular, the surgeon lowers tool 10 such that the lens capsule 106 is contacted by bands 34, 36 of burning element 30.
A low-voltage electrical pulse is then applied using foot-pedal control switch 90, and bands 34, 36 heat up such that a capsulotomy opening is burned in the lens capsule 106 where bands 34, 36 are positioned.
In order to obviate this situation, predefined points of weakness have been designed on the bands of the burning element. Referring to
Thus, the improved design shown in
The system and tool provide an effective and reproducible capsular opening in the lens and allows further steps of cataract surgery, such as phacoemulsification or an equivalent procedure, and removal of cataract material.
Thus, the tool of the present invention provides a very significant advantage when compared with capsulotomy tools of the prior art. The extendable-retractable burning element allows for performance of a capsulotomy in a quick and efficient manner, leaving a capsular opening that is clean and tear resistant. Moreover, the extendable-retractable burning element allows for entry into the eye via a corneal incision on the order of 1-2 millimeters, while allowing for a large capsulotomy, for example, 5-7 millimeters. Using the capsulotomy tool of the present invention, the surgical procedure is simplified, since the surgeon does not need to use a separate device for providing pressurized air to the surgical site.
Using the present invention, a complete circle or a complete oval-shaped searing takes place, so that there is no need for tearing of the lens using forceps, which would be difficult to perform and to control.
Having described the invention with regard to certain specific embodiments thereof, it is to be understood that the description is not meant as a limitation, as further modifications will now become apparent to those skilled in the art, and it is intended to cover such modifications as fall within the scope of the appended claims.